#include <cstdio>
#include <cmath>

int main( )
{
    int t;
    double x1, y1, x2, y2;
    scanf("%d", &t);
    while ( t-- )
    {
        scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
        printf("%.1lf\n", sqrt( ( x1 - x2 ) * ( x1 - x2 ) + ( y1 - y2 ) * ( y1 - y2 ) ));
    }
    return 0;
}
